Users often have a number of different communications devices for use in different contexts. For example the user may need have a requirement for mobility, so that he can access communications facilities from a number of different locations or whilst on the move. He may also, from time to time, need the ability to view a large screen or to generate “hard copy” output, requiring a printing capability. However, mobile devices have of necessity to be small, so large screens and printers are not normally associated with such devices. For this reason, a user may have a mobile device and a “desktop” device, the former having a smaller capability set than the latter. These devices function independently, which means the user has to define preferences and profiles for each device. It would be very convenient to unify a user's range of communication devices so they all share common preferences and act as a single “virtual” terminal in which the devices are differentiated by certain attributes such as mobility and output capabilities (screen size, availability of print facilities etc). Using this unified approach would allow the user to set profiles on this virtual terminal (by inputting an instruction using one of its constituent devices), to arrange that all devices are notified of these changes. This would allow a user to start an operation such as a computing session on one device and continue it on another.
For example, a user at home may have spent several hours searching web pages related to a particular topic and may then require access to these from work. As another example, a user surfing an internet site using a personal computer may wish to continue surfing whilst travelling. One device-unifying system is a product called “Hipbone”. This is discussed, for example, in    “E-Business Essentials” by Cade Metz, PC Magazine Jun. 21, 2000:    “People Who Need People” by Jim Sterne in Inc magazine—Sep. 15, 2000    “Many Happy Returnees”, by J Blackwood, Computer Shopper Aug. 8, 2001            “Digital Devices: Navigating the Web with friends” in Interactive Week, Feb. 4, 2000        
A similar system known as E-CoBrowse is described by Chong and Sakauchi at page 803-808 of the “Proceedings of the IASTED International Conference”—Las Vegas USA, November 2000.
Hipbone and E-Co-Browse are multi-party collaboration tools that enable individuals to co-browse the same web page and also send annotations and chat (to support their collaboration). They work purely at the URL level, whereby user's browsers are synchronised to request the same URL. They provide an Internet co-navigation service, which allows sales staff to ‘connect browsers’ with their customers and jointly view online product demonstrations, fill out complex web forms, and work through online transactions together. Among its key features are “True Shared Browsing”, which allows customer service and sales representatives (“agents”) to co-browse with customers and navigate the web together, and synchronises the agent's and customer's activities. Using this, real-time Interaction is achievable, all participants being allowed to direct the browser with the results echoed to each participant's browser. Hipbone's software supports functions such as authentication using “cookies” and order transaction processing. Using the shared browser allows form filling to be echoed to all participants. Forms can therefore be filled in using assistance from the serving participant (sales representative). Hipbone's high level architecture is based on a proxy mechanism. Basically, every web response is held on the central application server accessed by the shared browsers. However, there is no network based representation of the web session state (history, bookmarks, cookies, etc) and a user would not be able to switch from using one device to using another unless the second device had already been connected to the session from the outset.
Systems such as the “Netscape” flexible roaming access function provide data synchronisation so that a user can copy data between two devices—for example a laptop computer and a desktop computer—when they are connected to each other. In this way, if a user has modified a state using one of the devices whilst either or both devices are ‘offline’, that state can be updated on the other device once the offline devices are re-connected.
International Patent Specification WO00/70838 (Patil) describes a system that maintains a network-based record of the user's preferences and session information, allowing the user to access his personal information (eg. previous web pages, bookmarks, etc) from different devices. However, if the user, having begun work on one device, desires to continue on another device, he would have to store the results of the web session he was using, log-off one device and then go to the other device, relog in, and then select the stored details of the previous web session that he wishes to use.
None of these systems allow a user to continue an individual communications session on a different terminal to that on which the session was started.